GridPanel autoHeight fit problem

Hi.

I have a GridPanel within the layout 'fit' but I want it to fit a dynamic number of rows into the current visible area and not just i.e 10 rows if the continer is big enough to hold say 20 rows. I do not want scrollbars since I have a PagingToolbar, which also would need its pageSize dynamicly updated whenever the GridPanels container set/change size.
It is only okey for a scrollbar to show up if a plugin like RowExpander is used and someone expands a row.
Whenever the GridPanel container resize I want it to dynamicly update the number of visible rows and the PagingToolbars pageSize.